Since the effect of "Goddess of Whim" doubles the current ATK, not the original ATK, it's advised to buff her up as much as possible before flipping the coin. "United We Stand" used in conjunction with "Scapegoat" works wonders.
This card works well in an "Arcana Force" Deck because of its coin flipping ability. Also, like the "Arcana Force" monsters, it is a LIGHT Fairy-type monster.
"Second Coin Toss" will help you double the ATK of this card if you do not get the coin toss call correct.